Rigid thin sheet material and method of making it

Abstract

Lightweight flexure-resistant thin metal sheet is produced by passing flexible thin metal sheet between rolls having defined teeth, the teeth having radiused corners so that rows of projections are formed on both faces of the sheet without damage to the surface material or the rolls.

What is claimed is:  
     
       1. A method of making thin, flexible sheet metal rigid, the method comprising passing flexible sheet metal of relatively thin gauge between two rolls each having teeth, each tooth having four flanks and a top, the top having a peak and corners at the peak, each flank facing between an axial direction and a circumferential direction, the rolls being arranged so that the teeth of one roll extend into gaps between the teeth on the other, the top of the teeth being radiused at the peak and at the corners at the peak, the radius at the peak being from about 1.0 to about 2.5 mm and the radius at the corners at the peak being from about 0.2 to about 1.0 mm, the rolls being rotated at substantially the same speed about generally parallel axes to form rows of projections on both faces of the sheet metal passed therethrough, whereby the sheet is made rigid without damage to the street metal. 
     
     
       2. A method according to claim  1 , wherein each tooth has a bottom having corners that are radiused. 
     
     
       3. A method according to claim  1 , wherein the flexible sheet metal of relatively thin gauge used is of a thickness from 0.05 to 2.5 mm. 
     
     
       4. A set of rolls for use in cold rolling of plain sheet material, each roll having an outer surface, rows of teeth being present on the outer surface of the rolls, each tooth having four flanks of involute form and a top, each flank facing in a direction between an axial direction and a circumferential direction, wherein the top of the teeth each have a corner radius of from about 0.2 to about 1.0 mm, and a radius at a peak of the tooth of from about 1.0 to about 2.5 mm, the rolls being spaced apart in use by a distance such that the teeth on one roll extend into gaps between the teeth on the other roll, whereby projections are formed on both surfaces of the sheet material during its passage between the rolls, the teeth being arranged in generally parallel helical rows. 
     
     
       5. A set of rolls according to claim  4 , wherein each tooth has a bottom having corners that are radiused. 
     
     
       6. A sheet of sheet metal having projections on both of its surfaces, a corresponding depression being present on the surface opposite each projection, the sheet having been prepared by a method comprising the steps of passing a flat sheet of flexible sheet metal of relatively thin gauge between two rolls each having teeth, each tooth having four flanks and a top, the top having a peak and corners at the peak, each flank facing between an axial direction and a circumferential direction, the rolls being arranged so that the teeth of one roll extend into gaps between the teeth on the other, the top of the teeth being radiused at the peak and at the corners at the peak, the radius at the peak being from about 1.0 to about 2.5 mm and the radius at the corners at the peak being from about 0.2 to about 1.0 mm, the rolls being rotated at substantially the same speed about generally parallel axes to form rows of projections on both surfaces of the sheet metal passed therethrough, whereby the sheet is rigid without damage to the surfaces of the sheet metal. 
     
     
       7. A method of making thin, flexible sheet metal rigid, the method comprising passing flexible sheet metal of relatively thin gauge between two rolls each having teeth, each tooth having four flanks and a top, the top having a peak and corners at the peak, each flank facing between an axial direction and a circumferential direction, wherein the teeth each have a radius selected to maximize the local stretching of the plain sheet material and to minimize the thinning of the material and to reduce damage to the surface of the material. 
     
     
       8. A method according to claim  7 , wherein each tooth has a bottom having corners that are radiused. 
     
     
       9. A method according to claim  7 , wherein the flexible sheet metal of relatively thin gauge is of a thickness from 0.05 to 2.5 mm. 
     
     
       10. A set of rolls for use in cold rolling of plain sheet material, each roll comprising an outer surface, the rolls having rows of teeth on the outer surface, each tooth having four flanks of involute form and a top, each flank facing in a direction between an axial direction and a circumferential direction, wherein the teeth each have a radius selected to maximize the local stretching of the plain sheet material and to minimize the thinning of the material and to reduce damage to a surface of the material. 
     
     
       11. A set of rolls according to claim  10 , wherein each tooth has a bottom having corners that are radiused.